Unmanned space programs have several advantages over manned space programs, including the ability to run for several years and travel millions of miles from Earth without the need for food and water. Many exciting programs, both in deep space and near Earth, are sponsored by the National Aeronautics and Space Administration's Jet Propulsion Laboratory in Pasadena, Calif. including the Explorer program, the Magellan probe, CloudSat, and several Mars exploration programs.
Included in the Mars exploration programs are the Spirit and Opportunity rovers which have been exploring the surface of Mars. These robotic explorers have provided invaluable insight into the conditions on Mars and have been providing information and opportunities for research and development for today and for the scientists of tomorrow. The surface of Mars contains many surface features that indicate that water may have once existed on Mars. The Spirit and Opportunity rovers have conducted many experiments and discovered microscopic deposits on the Martian surface that indicates water once existed. Additionally, the surface of Mars is very dry, with large dust storms and high winds. The dust storms cause the rovers to lose power, while the high winds clean the dust off the rovers and enable them to continue working.
A capacitor is an electrical device designed to store energy in an electric field. Although the construction of capacitors may vary, the basis of a capacitor is two electrical conductors separated by a dielectric. The capacitance of a capacitor is greatest when there is a narrow separation between large areas of the conductors. An ultracapacitor is similar to a capacitor except that an ultracapacitor does not have a conventional dielectric. Instead, an ultracapacitor uses virtual plates that are different layers of the same substrate. These thinner layers can hold a small voltage, so several virtual plates can be combined to achieve very high power densities. Ultracapacitors have very high rate of charge and discharge. Additionally, ultracapacitors are very efficient, discharging approximately 95% of the energy used to charge the ultracapacitor.
A field-programmable gate array (FPGA) is an integrated circuit that is designed to be configured by the user of the FPGA using a hardware description language. This is opposed to an application specific integrated circuit (ASIC), which is fixed at the time of manufacturing. FPGAs contain programmable logic component blocks, including functional blocks and memory blocks, that can be connected together via a hierarchy of reconfigurable interconnects. FPGAs can be constructed via different processes, including SRAM, PROM, EEPROM, Flash, and Fuse. FPGAs can also be coupled with analog elements, including analog-to-digital converters and digital-to-analog converters, allowing the FPGA to operate as a system-on-a-chip.